Not Even Wrong

According to today’s New York Times, “string theory allows for a vast number – 10,500 – of possible ‘worlds’ wth different self-consistent sets of laws and constants.” If 10,500 is “vast”, I wonder what 10⁵⁰⁰ is? I also wonder how long it will take for the news to get through that actually this number is infinite, which is somewhat bigger than “vast”.

The Times piece is an extract from a recent Scientific American article on variable constants of nature. It also includes the standard claim that M-theory is “the best candidate for a theory of everything”, but perhaps an editor is editorializing by pairing this with the news from an astrologer that Saturn is going from Cancer to Leo and Mars is in Taurus. At least the astrologer is able to make predictions: “Many born during this summer of ’05 … will impact the world greatly in years to come.”

Here’s a collection of interesting things I’ve run across recently:

A website devoted to Hermann Weyl. The author is a religious sort, but of the good kind.

A movie taken at the 1927 Solvay conference. It is on the website for “The End of the Certain World”, which is a biography of Max Born. I’ve read the book and some of it is interesting, but I have little sympathy for one of its themes, that Born felt he didn’t receive enough recognition for his work (he got his Nobel Prize in 1954, long after many other Nobel prizes were given for quantum mechanics). Frankly I think any physicist like Born who had the incredible luck to be at Gottingen in 1925-26 should have spent the rest of his life thanking his lucky stars and not complaining about his career.

Harvard mathematical physicist Arthur Jaffe has a website. In particular the site has some interesting expository papers, including an autobiographical memoir about the IHES in the early 60s, a survey of constructive quantum field theory, and a work in progress, an introduction to quantum field theory from a rigorous point of view.

There’s a recent lecture by Eric Zaslow on Physics and Mathematics which he gives the supremely ugly name of Physmatics.

Some of the lectures from String Phenomenology 2005 in Munich last week are on-line. Lots of talks about flux vacua and the landscape, nothing that seems to have the remotest connection to physics. For a report from the conference, see Robert Helling’s weblog.

The talks from a conference held at Potsdam in April on Geometry and Physics after 100 years of Einstein’s Relativity are available.

The Bonn Arbeitstagung is a summer conference that was started by Friedrich Hirzebruch in the late fifties, and which often has been the site of announcements of important developments in mathematics. The 2005 Arbeitstagung ended last week and notes from the talks are on-line.

If you didn’t follow this a couple years ago, you can read John Baez’s detailed description of the Bogdanoff Affair. For more about my dealings with them, see here,, here, and here. If you want to read their stuff, go to the website of the Mathematical Center of Riemannian Cosmology which purports to be in Latvia.

In brief, the Bogdanovs are two brothers in France with a TV show who got Ph. D.s based on work which on the whole was complete nonsense. I’m not surprised that they managed to get Ph. D.s, and one of them was failed on his first attempt. It’s not unusual in academia to be faced with having to decide what to do with students who seem to be enthusiastic and work hard, but don’t perform at an acceptable level. There are lots of reasons to just pass them with the lowest possible grade (for one thing, this gets rid of them). One of my colleagues refers to this as the “infinitely elastic C-minus”.

What was disturbing about the Bogdanov story was that they managed to get papers published in six refereed journals, some of which were quite respectable. Some of these papers were essentially identical. After this story became public, the editorial board of one of the journals (Classical and Quantum Gravity) issued a statement saying that the paper they published shouldn’t have been accepted, and that they were taking (undisclosed) steps to change their refereeing process so this wouldn’t happen again. This seemed to me strong evidence that there is so much nonsense now in the theoretical physics literature that the refereeing system has broken down. Many referees are now either unwilling or unable to identify nonsense when they see it.

I had discussions about this with quite a few physicists at the time, and many of them took the position that this wasn’t such a big deal. Their attitude was roughly that “So what if these guys managed to get something nonsensical past some lazy referees? Everyone in the community can tell that what they wrote is nonsense and just ignores it. It’s not true that we can no longer tell nonsense from serious work”. I became somewhat convinced that I was being too harsh on string theorists and others when I thought that they had completely lost the ability to identify nonsense. Maybe the only scandal here was the laziness of referees, not the infection of the whole subject by nonsense to the point where lots of people can’t tell the difference. Well, I just changed my mind, clearly at least some string theorists can’t.

I feel somewhat constrained in what I can say about the details of this, due to the fact that someone I’ve been in contact with tells me of being threatened with a lawsuit by the Bogdanovs for having criticized them publicly. I’m also not about to engage in discussion of the details of their nonsense, which is what they, like all crackpots, really want. It’s just a complete waste of time.

These days some of the strongest criticisms of what is going on in string theory are coming from Lubos Motl’s weblog. His latest post asks what would have happened if currently fashionable ideas about string theory had appeared in the sixties before the standard model. They would have led to claims that many things about particle physics were inherently unpredictable, or dependent on the details of the earliest moments of the big bang. But when the standard model appeared in 1973, it made a wide range of detailed predictions of this type.

He also makes some remarkable statements about string dualities:

“Virtually all conjectured non-supersymmetric dualities (except a few exceptions in the topological context) are suspicious, and even those that are true may be true only because we define one of the sides to be dual to the other – while other equally consistent definitions may exist, too.”

and claims that in the mid-90s Tom Banks described how research on string dualities was being done as follows:

“If you can’t show that a conjectured duality is wrong in 5 minutes, it must be correct.”

Funny, I’d always suspected that was what they were doing, but I’d never have dared to suggest it. And by the way, I’m wondering if Jacques Distler has given up on string theory. It’s been several months since he’s written anything about strings, and a month since he’s written anything at all.

Lee Smolin wrote an interesting responses to comments in the comment section of my posting about his Physics Today piece entitled “Why No New Einstein?”. I’m reposting it here.

“Dear Peter and colleagues,

I am grateful for the attention given to my essay. I only want to emphasize a few points here. The main thing is that the essay is carefully written. It does not advocate more funds to LQG or any other program. It explicitly advocates more support and positions for young, ambitious theorists pursuing their own research programs who are unaffiliated with any larger program. Several proposals are made for how to accomplish this. I would hope that the focus of the discussion could be on these proposals.

-String theory is criticized in the essay mainly because it is currently sociologically dominant, and so subject to the problems mentioned. It was necessary to do so as many readers of physics today will be unfortunately unaware that there are any problems with string theory, or any viable alternatives. Anyone with a long enough memory will know that the sociological issues in high energy theory predate string theory, and have hurt physics in the past, i.e. in the case of S-Matrix theory.

-I hope I don’t have to say that I am not anti-string theory. My current last paper on the ArXiv is a technical paper in string theory, and I have 14 more in past years, plus 8 papers on related topics such as the landscape. I wouldn’t have written these papers if I didn’t think there was a good chance string theory is relevant to nature. The fact that someone like me who contributes sometimes, but not exclusively, to string theory, is not considered “a string theorist” is part of the sociological problems my essay criticizes. Similarly, the fact that one can elicit angry responses, and be called “anti-string” for carefully and correctly recounting the actual status of various conjectures is a sign of an unhealthy sociology. No one calls someone anti-LQG or anti-QCD when they do a similarly honest summary of what is known and not known in those fields.

-I would claim that the sociological issues mentioned in the essay have hurt string theory even more than they have hurt the alternative programs, because they greatly limit the range of ideas worked on, and because people with a lot of imagination and intellectual independence are either selected out or choose themselves to work within communities which are more friendly to diversity and imagination. As a result, key issues such as the question of a background dependent formulation, or perturbative finiteness, don’t get a lot of attention, in spite of their centrality for the whole program.

-I was grateful that someone noted the range of subjects at the LQG meetings. This was not planned, it is a natural outcome of the more open and curious atmosphere among people who work on the subject. We don’t believe we should have a meeting without inviting people from alternative and rival programs to report to us what they are doing, as well as to serve as critics. At the meeting in Marseille last May we even invited a persistent critic of LQG-Ted Jacobson-an early contributor who is now very critical of the subject-to give a talk to lay out his criticisms. I think it would be very good for string theory if the organizers of their meetings took a similar attitude.

-Someone asked for a blanket term for LQG, CDT, causal sets etc. We use background independent approaches to quantum gravity. There is a lot of interchange of ideas, techniques and people among these programs, and many of us have contributed to more than one. There is a very different intellectual climate, in which diversity, creativity and independence are strongly encouraged.

-Someone is asking for what is “LQG proper?” But the fact is that a lot of different things are now going on roughly under the name of or related to LQG. After all, this is now a community of > 100 people and there is no orthodoxy and no one trying to control what people work on. We agree generally on what has been achieved and what problems remain open, but not much beyond that. There is a healthy variety of approaches and attitudes towards the open problems. If there is one thing we all agree on it is that no approach is likely to achieve the right theory that is not background independent at its foundations. Come to the meeting and see what is happening.

-While the point of my essay was not to advocate more funding to any particular direction, if you ask me I will of course say that I think that people working on background independent approaches to quantum gravity deserve much more support. Among them are Loll and Freidel, that I am glad someone mentioned, but there are many others.

-I did not, as Lubos implies, advocate funding a large number of people who do nothing but think about the foundations of quantum theory. What I do advocate is much more support for the kind of person who might be inclined to work on foundational issues. These are deep and independent thinkers who believe that the road to progress in physics is confronting the hard problems directly. But there is no need to argue about whether more funding for foundations of quantum mechanics would be fruitful. The experiment has been done. For decades there was no support at all, and slow progress. Then, because of the possibility that quantum computers could break codes, there has been a lot of support for the last few years. And a lot of progress has been made, both experimentally and theoretically on aspects of foundations of QM.

-Although this essay was not written to advocate LQG, since it is attacked in response I should try to clear some things up. Someone asks for an accounting of the present status of the field. I among others, have given one in hep-th/0408048, shortly to be updated.

As to the issue of anomalies, i.e. the claim that we ignore the established knowledge that “INFINITE-DIMENSIONAL CONSTRAINT ALGEBRAS generically acquire anomalies on the quantum level…” is simply false. It is contradicted by rigorous existence and uniqueness theorems in LQG. As a few people do nevertheless take this seriously let me start from a point we can agree about and see if we can clear this up for good. I would hope we can all agree that:

1) The approach to quantization of constrained systems is different in string theory and LQG. The former approach depends on a gauge fixing that refers to a fixed background metric. It results in the construction of a Fock space. The latter is background independent and involves no background metric, no gauge fixing and results in a state space unitarily inequivalent to a Fock space.

2) There is a body of rigorous results that support each kinds of quantization. Hence it cannot be a question of which is correct mathematically. Both are correct, within their contexts. It is a question only of which construction is appropriate for which theories and which describes nature.

3) The treatment of constraints in string theory depends on certain technical features of 1+1 dimensional theories, particularly the fact that there is a gauge in which L_0 plays the role of a Hamiltonian and therefore should, in that gauge, be quantized so as to have a positive spectrum. The anomalies are not generic, as asserted above, rather they depend on the additional condition that L_0 should be a positive operator. There are other reps of Diff(S^1 ) that are non-anomalous but in which L_0 is not positive. So a choice is made in the standard quantization of string theory, which his motivated by the physics. This does not mean it is the right choice for all physical theories.

4) Conversely the existence and uniqueness theorems which support the LQG quantization work only in 2+1 dimensions and above for the reason that gauge fields don’t have local degrees of freedom in 1+1 dimensions. The existence theorems tell us that there are quantizations in 2+1 and higher of diffeo invariant gauge theories that have unitary, anomaly free realizations of diffeo invariance. The uniqueness theorem tells us that the resulting state space we use in LQG is unique.

5) Now it is true that Starodubstev and Thiemann have found it an interesting exercise to apply the LQG techniques to free string theory. Not surprisingly they get a theory that is unitarily inequivalent to the usual one. This does not mean that the usual quantization of string theory is wrong, nor does it mean that the LQG techniques are wrong when applied to other problems, where the existence and uniqueness theorems together with a large number of results prove their worth. All we learn is that the two quantizations are inequivalent, which was to have been expected.

6) With regard to the non-standard quantization, in which holonomies, but not local field operators are well defined, it is of course true that when applied to standard systems this leads to inequivalent results. “This apparently leads to unphysical consequences, such as an unbounded spectrum for the harmonic oscillator.” But, give me a break, do you really think someone is proposing to replace the standard quantization of the harmonic oscillator with the alternative one? What is being proposed is that the quantization used in LQG is well suited to the quantization of diffeo invariant gauge theories.

In case it is not obvious, let me emphasize that harmonic oscillators are not relevent here, and can play no role in a background independent quantum theory, precisely because the division of a field into harmonic modes requires a fixed background metric. Thus, the physics of the problem REQUIRES an alternative quantization.

The detailed motivation is, I think, well argued in the papers, and are supported by the results as well as the existence and uniqueness theorems. First, is well known that a complete coordinatization of the gauge invariant configuration space for a non-Abelian gauge theory requires the holonomies. Second, using them gives rise to the unitary non-anomolous reps of the spatial diffeomorphisms.

Nor is anyone proposing using non-seperable Hilbert spaces for the full theory, the point is that when one mods out by the piecewise smooth spatial diffeos one is left with a seperable Hilbert space.

I am frankly puzzled why someone who claims to know the literature well would throw up examples like the harmonic oscillator up in this context. I can try to understand their point of view, but it certainly reads as if they either are choosing to ignore the basic point, which is that background independent quantizations cannot use fock space, or they are looking to make debating points to impress ignorant outsiders. They must know comments like this are not going to influence experts, because they are, after all, taken from our own papers, written precisely because we wanted to clarify the difference between the new and standard quantizations and the limits of the applicability of each.

With regard to the sociology of the string-loop division, “Roughly speaking, string theorists are fundamentally particle theorists with a strong understanding of quantum theory, whereas loop people are gravitists with a background in GR”, this is a myth. Rovelli, myself and many other people in LQG were trained as particle physicists, myself at Harvard in the late 70’s. Most of the physical motivation for LQG comes directly from ideas about formulating gauge theories in terms of loops that were studied by Polyakov, Wilson, Migdal, Mandelstam, Neilsen and others. LQG is squarely an outgrowth of their intellectual tradition. The only thing we added was to correctly treat the diffeomorphism invariance exactly in the quantum theory. This led to new results just as the exact treatment of gauge invariance in lattice gauge theory led to new results. I would claim that we made progress in LQG precisely because we had a very good grounding in QFT.

String theory, as it is practiced, makes much more contact with the general relativity tradition, especially the once discredited tradition of extending general relativity to add dimensions and degrees of freedom in the search for a unified field theory. You are much more likely to read a paper which studies solutions to a generalizationsof the Einstein equations, with hbar=0, by a string theorist than by someone working on a background independent approach to quantum gravity.

This of course does not mean that string theory is wrong. But I believe it does mean that by enforcing a narrowly restrictive notion of what constitutes good work, the community of string theorists has hampered progress in string theory by excluding from consideration the lessons learned by attempts to do what string theory must do eventually if it is to be a real theory: which is to find a background independent formulation of a quantum theory of spacetime.”

A couple months ago when I was shocked to realize how close to reality my April Fool’s parody had been, I’d unsuccessfully tried to find out some more information about the Templeton conference at Stanford that Mark Trodden had mentioned here. There’s now something about it on the Templeton website. It was part of Templeton’s Humble Approach Initiative which has as its goal “to bring about the discovery of new spiritual information.”

The conference was called Multiverse and String Theory: Toward Ultimate Explanations in Cosmology, and brought together various landscapeologists (including most of the Stanford theory group). One of the other participants was the Rev. Dr. Rodney Holder, an Anglican priest who believes that science supports Christian belief, and that “modern cosmology has reinvigorated the traditional argument for the existence of God from design”. He has written an article on miracles that won an award from the Templeton Foundation, and has a new book out entitled God, the Multiverse and Everything: Modern Cosmology and the Argument From Design, which argues for Intelligent Design.

Lee Smolin has a piece in the latest Physics Today entitled Why no “new Einstein”?. Unfortunately it’s only available to Physics Today subscribers, although Lee tells me he will see if he can put it on-line on his web-page. Tony Smith previously mentioned this in a comment to an earlier posting.

The problem Lee addresses seems to me to be an extremely important one. Pretty much every knowledgeable particle theorist that I talk to these days, string theorist and non-string theorist, agrees that current ideas about how to go beyond the standard model are not working very well. Everyone hopes that some big new idea will come along and show the way forward, with people often wistfully speaking about how maybe some bright post-doc out there may be at this very moment working on the needed new idea. The problem with this is that what is needed is probably something quite different than any of the current popular research programs, and finding it may be difficult enough to require someone’s concerted effort over quite a few years. If this is so, it’s very hard to see how anyone on the standard career path in the US is going to be able to do this. A young post-doc here generally only has a couple years in between needing to apply for new jobs, and if he or she were to devote those years to working hard on a very speculative new idea, this would most likely be suicidal for their career.

Some will argue that young theorists should just try and work on speculative ideas in their spare time, spending enough time working on currently fashionable topics such as string theory to impress people enough to ultimately get a permanent job, at which point they can work more seriously on their speculative idea. The problem with this is that getting up to speed and participating in the latest trendy research in string theory is a very demanding task, one that isn’t likely to leave much time or energy for other projects. In addition, it’s not at all clear that being willing to work hard on an obviously failed research program like string theory is consistent with having the intelligence and drive needed to do something really new. Instead of working on string theory, a young theorist could try and work on one of the other popular topics such as cosmology or phenomenology, but these are very different subjects than fundamental work in quantum field theory. A young theorist would be more likely to be able to find the necessary time if he or she went to work as a night-time security guard.

Lee makes several excellent proposals about how to restructure the way hiring is done to encourage young people who want to try something new. I hope he has some success in getting the powers-that-be to realize what a serious problem the field is facing and take some of the actions he suggests.

Two completely unrelated topics:

Lubos Motl has a posting about the Harvard Commencement, where it seems they’re giving Witten an honorary degree (Columbia already did this in 1996). He also writes about a new web-site for the Sidneyfest, the conference in Sidney Coleman’s honor that was discussed here and on many other weblogs. The new web-site includes copies of letters to Coleman from people who couldn’t attend the conference. In one of them Greg Moore recalls and reproduces Coleman’s proof from the late eighties that string theory is the unique theory of nature.

For something pretty weird, see this from the latest Notices of the AMS. There’s more about the activities of its author on Robert Helling’s weblog. The new issue of the Notices also contains an article about the 2006 NSF budget request for mathematics.

Update: Lubos Motl has his own comments on Smolin’s article, together with a link to some site where someone seems to have posted the article without attribution.

Nature this week has an editorial about Fermilab entitled All or Nothing at Fermilab associated with a news article Fermilab: High-risk physics. The article and editorial are about the fundamental problem facing Fermilab: in a few years the high energy frontier will move to the LHC at CERN, with many physicists leaving Fermilab. The future of the lab remains up in the air, as the only viable plan for a new high-energy accelerator is the ILC project, and this would require massive new funding which is still quite uncertain. While SLAC has diversified into X-ray physics, Fermilab remains committed to operating at the highest energies. Many people worry that if the ILC is not funded or delayed for many years, Fermilab will be in a difficult position, and a prime target for budget cuts.

This week the lab is hosting the annual “User’s Meeting”. Presentations about current and future activities at Fermilab are available on-line.

I spent most of last week commuting down to Rutgers to participate in a workshop on “Groups and Algebras in M-theory”, organized by Lisa Carbone. Lisa was a student of Hyman Bass’s here at Columbia some years back, and in recent years has been working on Kac-Moody groups and algebras over finite fields.

Much is known about one special class of Kac-Moody algebras, the so-called affine Lie algebras. These are basically Lie algebras associated to loop groups, with a central extension. The study of the representation theory of these algebras is closely connected to quantum field theory in 2d space-time dimensions, and my first talk was about this topic. For more details about this, from the point of view I was taking, see the remarkable book by Pressley and Segal called “Loop Groups”, lecture notes from 1985 by Goddard and Olive at the Erice Summer School and Srni Winter school (see Int. J. Mod. Phys. A1:303, 1986), and Witten’s paper “Quantum Field Theory, Grassmanians and Algebraic Curves” in Communications in Mathematical Physics, 113 (1988) 529-600.

An elaboration of these ideas in one direction leads to the concept of a “Vertex Operator Algebra” (first introduced by Richard Borcherds), and the study of these was pioneered by Jim Lepowsky, who also participated in the workshop, together with his ex-student and now Rutgers faculty member Yi-Zhi Huang. Several other current and ex-students of Lepowsky and Huang were also there and gave talks. For more about vertex operator algebras, see the recent short review by Lepowsky, or the materials on Huang’s web-site. A VOA is essentially the same thing that Beilinson and Drinfeld call a chiral algebra, and these have applications in the geometric Langlands program.

What Lisa is really interested in is the non-affine case, where relatively little is known. Non-affine Kac-Moody algebras and groups seem to have no known tractable realizations, and many basic questions about both the algebras and the groups, as well as their representations, remain open. In recent years several of these algebras have been conjectured to have something to do with M-theory, most notably E₁₁, and the study of this connection has been the main focus of the work of Peter West, who gave a series of talks at the Rutgers workshop. For some more about this, see his recent papers, especially one on The Symmetry of M-theories. West’s graduate student P. P. Cook also has a weblog, and recently wrote a posting explaining a bit about this topic.

Greg Moore was at many of the talks and kept the speakers honest. He gave a fast-pace talk covering some older work, roughly the same material as in his paper with Jeff Harvey entitled Algebras, BPS States and Strings. I gave a second talk explaining a bit about my point of view on the Freed-Hopkins-Teleman theorem and its relation to representation theory and QFT.

After the talks Thursday afternoon there was a discussion section on what is going on with string theory, supersymmetry, and mathematics. No one was willing to defend work on the “Landscape” and I was surprised to find myself pretty much in agreement with quite a few people there about the way string theory has been pursued in recent years. On the whole the mathematicians are kind of bemused by the whole string theory controversy. The subject has certainly led to some very interesting and important mathematics, and they are happy to concentrate on that, although interested to hear about the controversy surrounding string theory in physics.

The Pacific Institute for Theoretical Physics, based at UBC in Vancouver, held a Showcase Conference a couple weeks ago, which was supposed to “celebrate the exciting new developments taking place in theoretical physics”. According to the organizers there are lots of exciting new developments in string theory, since six of the invited speakers (Myers, Ooguri, Randall, Schwarz, Shenker, Susskind) spoke on that topic, but no one at all spoke about elementary particle physics. There were also quite a few talks on condensed matter physics.

The talk of John Schwarz consisted mainly of the standard recounting of the history and basics of string theory that anyone who has been to conferences like this has heard a hundred times. This part stopped with Maldacena’s work more than 7 years ago. On more recent topics, about the anthropic explanation of the cosmological constant, Schwarz says: “Is there another explanation? I hope so.” He ends by putting up a long list of questions about string theory, more or less the same list everyone has had for twenty years now.

Steve Shenker spoke on Emergent Quantum Gravity, with “emergent” the new buzzword of the field. There was a separate workshop on emergence overlapping with the Showcase conference, organized by Phil Anderson and others, with Susskind the only string theorist allowed to speak there. Shenker introduced a new terminology to justify string theory: it is “An algorithmically complete, consistent description of quantum gravity”, although he does add the caveat “In certain simple situations (like flat space)”. By this I guess he is trying to get around the problem of how to claim that your theory is complete and consistent when you don’t know what it is. The idea is that at least you have an algorithm for doing computations. Perhaps he means perturbative string theory, although that is neither consistent nor complete (the expansion in the number of loops diverges). Perhaps he means a non-perturbative formulation like a matrix model, which works in 11 flat dimensions, but then he really should note that he’s not talking about quantum gravity in four dimensions, which is what most people care about.

There was an interesting panel discussion on The Theory of Everything?, which was moderated by Steve Shenker. He seemed mainly interested in making the obvious point that string theorists weren’t actually claiming that their theory explained anything about, say, biochemistry. The panel was actually balanced between string theory enthusiasts (Shenker, Schwarz, Randall), and skeptics (‘t Hooft, Unruh, Wald). Some of Shenker’s introductory remarks are inaudible, but he did repeat his claim about the “algorithmically complete” nature of string theory. “t Hooft had some quite interesting comments. He recalled that at a conference back in 1985 he had been the only one who didn’t think that twenty years later string theory would have solved all the problems of particle physics, noting that it was now 20 years later, he had been right, everyone else at the conference wrong. He was making the point that string theory now is extremely far from solving any problems in particle theory, and one can’t tell if this situation will change in 20, 200 or 2000 years. He tried to say some positive things about string theory, but they were pretty half-hearted. For instance he noted that dualities were very interesting, but they linked one ill-defined theory to another ill-defined theory. He also noted that in its present formulation string theory is only defined on-shell, which he takes as meaning that it doesn’t give a true local description of what is going on. He has reasons for being suspicious of people who claim that all one needs is an on-shell theory.

Schwarz attributed the TOE terminology to John Ellis. He said that he feels string theory is very far from explaining anything about elementary particle physics, that it was “almost hopeless to find the right vacuum”. He described what landscapeologists are doing in a skeptical tone, but didn’t actually criticize this. Answering ‘t Hooft, he claimed that back in 1985 he and Mike Green were actually more pessimistic than most other people about the prospects for getting quick results out of string theory.

Bill Unruh made the standard criticism that what is wrong with string theory is that string theorists are motivated by beautiful math, not physics. He doesn’t seem to have noticed that few string theorists are now doing math, since unfortunately most of them have taken to heart the criticisms of people like him. The failure of string theory has unfortunately reinforced the skepticism of many people like Unruh about the use of math in theoretical physics.

Wald quoted what sounded like a recent description of what string theorists think they are doing, then revealed that his quotes were from the 19th century, and referred not to string theory, but to the popular theory of the time that atoms were vortices in the ether. He deftly made the point that it is quite possible, if not likely, that string theory is just as wrong an idea as the vortex one.

Lisa Randall made some defensive comments about string theory as a guide for future research, even if it turns out not to work. These included the bizarre political analogy that it was wrong to worry about string theory ruining the credibility of physics, because, after all, the bogus WMD business didn’t seem to have hurt Bush’s credibility.

There were then some questions and comments from the audience. Susskind was in the first row, looking very peevish and defensive. He kept repeating that the field of theoretical physics had “no real choice but to track this down”, meaning to investigate the infinite landscape, and that this would take the efforts of many physicists. He explicity worried that funding agencies would not give any grants to anyone working on the landscape, to which Unruh responded that the shoe was really on the other foot, with some NSF panelists refusing to fund anyone who wasn’t doing string theory.

The conference web-site also includes an explanation of string theory which claims that in recent years string theory has “evolved very rapidly”, that the reason it can’t be tested is because of the small distance scales involved, and that it may be testable by observing a “5th force”, all of which is a load of nonsense.

Lubos Motl has an interesting post going over all the possible ideas he can think of that might lead to the next superstring revolution. Needless to say, they all sound extremely unpromising to me. Judge for yourself. He also quotes the promotional material for Susskind’s book due out late this year. It seems that “the Laws of Physics as we know them today are determined by the requirement that intelligent life is possible”.